The technology of the present invention relates to the treatment, prevention, and/or decrease in the incidence of infection by a pathogenic agent. In particular, certain aspects of the present technology relate to the prevention of the colonization by a pathogen.
Examples of pathogens include microorganisms such as bacteria, viruses, protozoa, or fungi that can cause disease. Pathogens may be endogenous or exogenous. The clinical presentation of an infectious disease state reflects the interaction between the host and the microorganism. This interaction is affected by several factors including for example the host immune status and microbial virulence factors. Signs and symptoms can vary according to the site and severity of infection. The responsibility of the medical microbiology laboratory includes not only microbial detection, isolation, and identification, but also the determination of microbial susceptibility to select antimicrobial agents.
Antimicrobial agents, or antipathogen agents, generally kill, slow the growth, and/or inhibit the pathogenic action of microbes or pathogens. Included among the antimicrobial agents are antibacterial agents, antiviral agents, antifungal agents, and antiparisitic agents. In spite of the availability of effective antimicrobial drugs and vaccines, the battle against infectious diseases is far from being over. Particularly in developing countries, the emergence and spread of antimicrobial resistance is threatening to undermine the ability to treat infections and save lives. The development of new families of antimicrobials throughout the 1950s and 1960s and of modifications of these molecules through the 1970s and 1980s allowed the medical community to believe that it could always remain ahead of the pathogens. However, the pipeline of new drugs is running short and there is an impetus to develop new antimicrobials to address the global problems of drug resistance.
In addition to establishing effective public health policies regarding the proper use of antimicrobial agents, there is a general consensus that continued research and development of new antimicrobial agents is vital to keeping pace with the evolution of resistant pathogenic microbes. Over and above research regarding pharmacokinetics, pharmacodynamics, and dosage regimens, research into the identification and function of novel genes to provide the industry with new and defined targets for therapeutic intervention is paramount.
Pathogens constitute a diverse set of agents. There are correspondingly diverse ranges of mechanisms by which pathogens cause disease. The survival of most pathogens require that they colonize the host, reach an appropriate niche, avoid host defenses, replicate, and exit the infected host to spread to an uninfected one. In particular, many bacteria have unpredictable susceptibilities to antibacterial agents, and antibacterial resistance continues to cause a large number of sustained infections and deaths. Evolution of bacteria towards resistance to antimicrobial drugs, including multidrug resistance, is unavoidable because it represents a particular aspect of the general evolution of bacteria that is unstoppable. Resistance to antimicrobial drugs in bacteria can result from mutations in housekeeping structural or regulatory genes. Alternatively, resistance can result from the horizontal acquisition of foreign genetic information. The two phenomena are not mutually exclusive and can be associated in the emergence and more efficient spread of resistance.
The progression of a pathogenic bacterial infection to a disease state generally includes entry, colonization, and growth. Most infections begin with the adherence of bacteria to specific cells on the mucous membranes of the respiratory, alimentary, or genitourinary tract. Many bacteria possess surface macromolecules that bind to complementary acceptor molecules on the surfaces of certain animal cells, thus promoting specific and firm adherence. Certain of these macromolecules are polysaccharides and form a meshwork of fibers called the glycocalyx. Other proteins are specific, (e.g., M-proteins on the surface of Streptococcus pyogenes) which facilitate binding to the respiratory mucosal receptor. Also structures known as fimbrae may be important in the attachment process. For example, the fimbrae of Neiseria gonorrhoeae play a key role in the attachment of this organism to the urogenital epithelium where it causes a sexually transmitted disease. Also, it has been shown that fimbriated strains of Escherichia coli are much more frequent causes of urinary tract infections than strains lacking fimbrae, showing that these structures can indeed promote the capacity of bacteria to cause infection.
If a pathogen gains access to tissues by adhesion and invasion it typically multiplies by a process called colonization. Colonization typically requires that the pathogen first bind to specific tissue surface receptors and overcome any host defenses. The initial inoculum may or may not be sufficient to cause damage. A pathogen generally must grow within host tissues in order to produce disease.
The human CEA-protein family of proteins (Carcinoembryonic antigen-related) is expressed on the internal cellular lining of the gastrointestinal tract and is most likely exploited by some bacterial pathogens for colonization. The human CEA-protein family includes several distinct proteins, such as the CEACAM1 (Carcinoembryonic antigen-related cell adhesion molecule 1), CEACAM3, CEACAM5, CEACAM6 and CEACAM8. Each of these proteins has a unique expression distribution among different cells and tissues, and can interact with various target molecules, including some of the CEA protein themselves. These interactions generate a broad variety of biological functions. So far, several functions have been attributed to CEA proteins, including without limitation, the regulation of endocrine, immunologic, and cancerous processes, as well as tissue structure organization.
Various CEA proteins interact with different bacterial strains, including without limitation, some E. coli (an entire group of enteric bacteria), N. gonorrhea (causes gonorrhea), N. meningitides (causes severe meningitis), M. catarrhalis (causes upper respiratory infections, pneumonia and otitis media). These pathogens generally must first adhere to the appropriate internal cellular lining before causing the actual disease, in a process generally known as colonization
Adding to the medical community's repertoire of available antipathogen agents, and that community's ability to fight the problem of antibacterial resistance, the present technology is directed in part to the development of new antipathogen agents derived from the human CEA-protein family of proteins or derivatives thereof. In particular, the present technology is directed to the use of human CEA-proteins, or derivatives thereof, for the prevention or retardation of a pathogenic infection, including bacterial and viral infection, and the subsequent progression to a virulent disease state.